[comp.sys.ibm.pc.misc] Found bug on all Laserjets

twong@civil.ubc.ca (Thomas Wong) (03/13/91)

We've been having funny problems with our Laserjets (from Laserjet IIs
to Laserjet III) all these years and I think we've finally found what 
is wrong. We have a lab of computers and every once in awhile, 
the Laserjet would stop printing graphics (regardless of program). 
It would either come out with a blank sheet or a 21 ERROR.
We've tried rebooting (computer & printer) all sorts of things. So
what we've adapted to doing is label that printer as text printer
only until the graphics comes back. This has been happening on all
Laserjets so we know it's not a problem with one printer. So finally,
one guy saw a pattern. And after many tests, we found the problem.
If someone sets a landscape font on the Laserjets panel, or sets
orientation=L on Laserjet III, the graphics no work. And since Lotus
123 is used extensively here, printing of worksheet in landscape mode
is a common thing. Then when someone sets thing back to portrait on
the printer side, things work again. We've tested this on all our
Laserjets and the same thing happens (some have garbage printout
instead of blank sheet or 21 ERROR though). So I think we've found
a bug in the way Laserjet does things. I can't see why this won't
work. And I can't understand why it hasn't been detected/fixed by
Laserjet III. Can others please confirm this bug?

On Laserjet II, choose a landscape font on panel (something like I12
would do), then print graphics with your favorite graphics program 
(not word processor which somehow works!)

On Laserjet III, choose orientation=L, then print graphics using your
favorite graphics program (again not word processor).

Then we can decide to flame HP or not. ;)

Thomas.

josephc@nntp-server.caltech.edu (Simplelogic (Joseph)) (03/13/91)

The problem, as I understand it, is not a bug, but rather just the way
HP defined how rasterize graphics should be handled by the PCL.

The graphics output is independent of the font orientation, and will
always go from the upper-left corner of a portrait sheet to the right-
most corner, and repeat for the next lower raster...

The problem is that when in the landscape mode, the "cursor" is at a wrong
location on the paper, and so when the HP tries to move the cursor as
it does the raster graphics, it places the graphics where no paper exist,
causing an error.

It's been some time since I've played with LJ's (ever since the original
Laser Jet NON-plus)...  So some of the things I said may or may not apply,
(or even be correct - my memory fades quickly sometimes...) Boy, time sure
flies when you're printing up a storm...

--Joseph
-- 
Joseph I. Chiu, Department of Computer Science, Calif. Inst. of Technology
1-57 Fleming House, Caltech, Pasadena 91126.   (818) 585-0393
josephc@coil.caltech.edu               ...Just another lost soul in the universe

cctr132@csc.canterbury.ac.nz (Nick FitzGerald, CSC, Uni. of Canterbury, NZ) (03/16/91)

In article <1991Mar12.212111.28413@unixg.ubc.ca>, twong@civil.ubc.ca
(Thomas Wong) writes:
 
> We've been having funny problems with our Laserjets (from Laserjet IIs
> to Laserjet III) all these years and I think we've finally found what 
> is wrong. We have a lab of computers and every once in awhile, 
> the Laserjet would stop printing graphics (regardless of program). 
> It would either come out with a blank sheet or a 21 ERROR.
> We've tried rebooting (computer & printer) all sorts of things. So
> what we've adapted to doing is label that printer as text printer
> only until the graphics comes back. This has been happening on all
> Laserjets so we know it's not a problem with one printer. So finally,
> one guy saw a pattern. And after many tests, we found the problem.
> If someone sets a landscape font on the Laserjets panel, or sets
> orientation=L on Laserjet III, the graphics no work. And since Lotus
> 123 is used extensively here, printing of worksheet in landscape mode
> is a common thing. Then when someone sets thing back to portrait on
> the printer side, things work again. We've tested this on all our
> Laserjets and the same thing happens (some have garbage printout
> instead of blank sheet or 21 ERROR though). So I think we've found
> a bug in the way Laserjet does things. I can't see why this won't
> work. And I can't understand why it hasn't been detected/fixed by
> Laserjet III. Can others please confirm this bug?
> 
> On Laserjet II, choose a landscape font on panel (something like I12
> would do), then print graphics with your favorite graphics program 
> (not word processor which somehow works!)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [Aha !]
> On Laserjet III, choose orientation=L, then print graphics using your
> favorite graphics program (again not word processor).
> 
> Then we can decide to flame HP or not. ;)

Do not flame HP.  This "bug" is a well-documented feature of the LasrJets
*since the original model*.  It is due to things called the "unprintable
regions" of a page, and to the extent that anything has a bug, it is the
graphics applications you use, which obviously, incorrectly assume that
LaserJets will always be in portrait orientation, or fail to correctly set
the printer back to portrait mode.  (One could argue that Lotus 123 is
bugged for not resetting the printer at the end of a print job, but we
won't go into that here.)

The Tech Ref for our LJ+ (which also covers the original LJ and the LJ500+)
clearly states, in a box, under *NOTE* in large letters:

"The raster motion is perpindicular to the paper's motion through the printer.
*Portrait mode is recommended for printing simple raster graphics
applications.*  [Emphasis HP's]  To print raster graphics in the landscape
mode, you must first move the cursor to the right ([for] at least the length
of the graphics) using the horizontal cursor positioning escape sequences. 
Otherwise, the printer will attempt to print your graphics in the
unprintable region and your data will be lost."

[Reproduced without permission, but for a good cause.]

The real giveaway that there is nothing wrong with the printer, but with your
graphics app's, and maybe with 123, is the fact that your word processor/s
work fine (see highlighted line).  This one fact should have made you suspect
other than the printer.  I don't know what the solution to your problem is,
maybe buy better graphics software, or fiddle round with 123's and the
graphics apps' printer drivers so that the "reset on completion" code (if they
have one) and the "initialize printer" code are setup appropriately, to bring
your LJ back into a known state.  "Good" software allows you to mod its
printer drivers - but then again, good software doesn't assume that a printer
is in a given state to start with!

If all else fails, read the LJ Manuals - you might learn something about what
they were designed to achieve, 8-).

---------------------------------------------------------------------------
 Nick FitzGerald, PC Applications Consultant, CSC, Uni of Canterbury, N.Z. 
 Internet: n.fitzgerald@csc.canterbury.ac.nz        Phone: (64)(3) 642-337